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Why are head/eye movements so important?
       
The swim effect of progressive lenses is mainly due to head
movements, while, at the other end of the spectrum, the more a wearer
moves his eyes, the greater the lens area the eyes explore. So in order
to optimize a progressive lens, it is essential to know the patients
unique vision strategy.
All Varilux lenses are based on the wearer’s physiological needs.
The designs of the first five generations of Varilux lenses have been
constantly improved based on the common fundamental needs of large
populations of presbyopes.
Today, Varilux Ipseo lenses consider the individual physiological
differences of each and every lens wearer.
Advanced research demonstrates that eye and head movement ratio have a
direct correlation with the way the surface of the lens is used and how
objects are perceived :
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Eye movements have a direct
influence on perception of fields vision. |
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Head movements have a direct
influence on perception of swim effect. |
With eye-movers, the eyes scans a large
surface of the lens to explore the surroundings.
The more eye movement, the more critical it becomes to maximize the
width of vision fields for optimum comfort in dynamic vision.
With head-movers, the eyes use only the central portion of the lens for
foveal vision.
The more head movement, the more critical it becomes to minimize minor
distortions for optimum comfort in dynamic vision. The design must be
very soft in periphery to minimize the 'swim' effect.
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